SNP Shot: Genomic Insights

Hereditary neuralgic amyotrophy (HNA) is a condition marked by recurring episodes of intense pain and muscle atrophy, primarily affecting the shoulders and arms, either unilaterally or bilaterally. This neuralgic pain originates from one or more nerves and often lacks a clear underlying cause. The brachial plexus, the network of nerves involved in HNA, is responsible for controlling both movement and sensation in the shoulders and arms.

Individuals with HNA typically experience their initial attacks during their twenties, although onset can occur as early as one year of age. These attacks can arise spontaneously or be triggered by stressors such as intense physical activity, childbirth, surgical procedures, exposure to cold temperatures, infections, vaccinations, or emotional distress. While the frequency of these episodes tends to diminish with age, many individuals are left with lasting issues, including persistent pain and impaired mobility, which worsen over time.

A typical HNA attack begins with severe pain, often on one side of the body, with the right side being more frequently affected. This pain can be difficult to manage with medication and usually lasts for approximately one month. Within hours or up to two weeks, the muscles in the affected area begin to weaken and waste away (atrophy), leading to restricted movement. This muscle wasting can alter posture and the appearance of the shoulder, back, and arm. A common sign is scapular winging, where weakened shoulder muscles cause the shoulder blades (scapulae) to protrude from the back. Other symptoms of HNA may include reduced sensation (hypoesthesia) and abnormal skin sensations like numbness or tingling (paresthesias). Areas beyond the shoulder and arm can also be affected.

Some individuals with HNA, within certain families, exhibit distinctive physical traits. These can include short stature, extra skin folds on the neck and arms, cleft palate, bifid uvula, and partial syndactyly. Distinctive facial features may be present as well, such as ocular hypotelorism, short palpebral fissures with epicanthal folds, a long nasal bridge, a narrow mouth, and facial asymmetry.

Inheritance:

HNA follows an autosomal dominant inheritance pattern. This means that inheriting just one copy of the mutated gene in each cell is enough to cause the disorder.